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Stormwater is a significant transport medium for pollutants to recipients located near cities. Substances commonly found in stormwater include nutrients, metals, organic substances and particles. A group of pollutants detected in stormwater are per- och polyfluoroalkyl substances (PFAS). PFAS is a group of chemicals which have been proven to have harmful effects on health, such as endocrine disruptive effects. The most sensitive considered parameter today is effects on the immune system, but a few of these substaces are also classified as carcinogenic or potentially carcinogenic. The distribution of PFAS to the environment is significant from both new and historical uses and sources, which continue to contribute to the environment due to high persistence of PFAS. The most significant point sources of PFAS in stormwater are industrial processes and manufacturing of PFAS-containing products, firefighting foam and hydraulic oil. Atmospheric deposition, building materials and traffic also contribute but in a smaller scale.  This thesis is based on a case study of a Swedish stormwater system and is aimed to evaluate which concentrations that can be classified as elevated in the stormwater system. Another aim is to investigate various remedial measures against the elevated levels of PFAS in the stormwater system. This was accomplished by a literature study of remediation techniques for PFAS applicable to a case study of an investigated stormwater system. The case study was carried out in different parts to estimate the risks and possible measures. The parts were action levels, site-specific guideline values, sampling, requirements for actions or remediation, and possible remediations techniques. Action targets and site-specific guideline values were developed based on literature and results obtained using a conceptual model. The action target was stated as follow: Stormwater must not contribute to the distribution of per- och polyfluoroalkyl substances which in a long term can result in levels in surface water that pose a risk to human health. The site-specific guideline value of 4,4 ng/L PFOA-equivalents at the outlet of the storwater, was developed based on background levels and environmental quality standards from EU:s water directive for surface water.  Sampling and analysis of 22 different PFAS compounds was carried out at 10 different sampling locations in the actual stormwater system of the case study. The measured levels were compared to the site-specific guideline value, and an assessment of requirements for actions or remediation was carried out. The measured levels in the stormwater system were calculated, 5,76 ng/L PFOA-equivalents. Finally, an investigation was done of possible remedial actions and suitable remediations techniques. The stormwater system needed further investigations to make a legitimate decision about the need for stormwater treatment of PFAS. Investigations of potential point sources were suggested as adequate in order to apply the most resource efficient remedial action. Various remedial techniques were also considered for the stormwater system. The techniques were evaluated based on the criterias's; remedial capacity, water matrix, estimations of captial- and operating costs, energy requirements and availability on the market.

Perfluorinated sulfonic acid (PFSA) ionomer membranes demonstrate great potential for use in proton exchange membrane fuel cells (PEMFCs) due to their favorable electronic properties and excellent efficiency. However, the assignment of key vibrational transitions such as the symmetric sulfonate and ether stretches is not yet fully understood depriving researchers of a quick and simple technique for analyzing morphological changes. The symmetric sulfonate stretch could be used to track changes in the ionic clusters formed within the membrane while the ether stretch will provide insight into the largely semi-crystalline PTFE phase. Alterations in either regime will affect both ion transport and mechanical properties and produce a major shift in device performance. This study focused on predicting the vibrational transitions for Aquivion, 3M PFSA, and Nafion using density functional theory (DFT) with the bulk being performed using the same functional and basis set combination, B3LPY/6-31+G*. For all three ionomers, the predicted vibrational transitions were affected by changes in both the conformer and solvation method with water being used as the solvent. Despite the noted changes, both vibrational transitions were determined to be within the range of 970-1100 cm-1 with the symmetric sulfonate stretch present at around 970-1010 cm-1 and the ether stretch observed at around 1050-1100 cm-1 with solvation present. While the calculated peak positions mirror those found in the experimental spectra within the literature, the traditional normal mode assignments do not match those predicted by our calculations. However, recent studies have hypothesized that these vibrational transitions are coupled, which could explain why they have been so difficult to assign. / Master of Science / Perfluorinated sulfonic acid (PFSA) ionomer membranes show great promise for use in proton exchange membrane fuel cells (PEMFCs) due to their excellent efficiency. However, the current techniques used to determine changes in structural configurations require sophisticated equipment and trained personnel to operate. Simpler techniques exist wherein the vibrations of certain bonds can be measured upon exposure of the sample to measured amounts of infrared light. The problem with this technique is that researchers currently do not fully understand at what wavelengths certain portions of the polymer known as functional groups will vibrate. These vibrations are also known as vibrational transitions. This study was undertaken to predict through numerical solutions to the Schrödinger equation at what wavelengths two particular vibrational transitions would occur for three common ionomers, Aquivion, 3M PFSA, and Nafion. For all three structures, the positions of these transitions mirrored that observed within the literature although the functional groups assigned to these positions did not match with those identified by our calculations. However, recent studies have indicated that these vibrational transitions occur at the same positions, which could explain why they have been so difficult to assign.

The occurrence of chemical contaminants in the environment is one of the key issues the world isfacing today. Special effort has been put on the screening of endocrine disrupting compounds(EDCs), substances that have been shown to have adverse effects on the endocrine system. EDCs are mainly found in pharmaceuticals and personal care products (PPCPs), but also other products covering almost all categories of our daily life. EDCs can be both organic, such as the persistent organic pollutants (POPs), and inorganic, e.g. heavy metals. Today, all kinds of EDCs are currently being investigated on a large scale. Two EDC sub-categories that have gained increased public attention during the last years are organic flame retardants (FRs) and per- and polyfluoroalkylated substances (PFASs). Both categories have shown to be bioaccumulating, persistent and toxic, which has led to banning of several substances in both categories. However, as both FRs and PFASs are considered to be emerging POPs, their fate and behaviour in the environment are still in great need of research. FRs and PFASs often end up in surface waters due to their disinclination of getting removed in waste water treatment plants (WWTPs) and their persistence. Thus, the objective of this project was to provide a snapshot of the current situation of FRs and PFASs in Swedish rivers, including both smaller streams and bigger rivers. Grab water samples were taken at 25 sites for FRs and 44 for PFASs in rivers all over Sweden. The results showed that sparsely populated areas such as the northern part of Sweden generally showed lower concentrations of PFASs in the water than the southern part did. The summarised concentrations of FRs ranged from 37 ng L-1 to 4.6 μg L-1, and from 0.59 ng L-1 to 59 ng L-1 for the detected PFASs, which was in good comparison to previous studies carried out on surface water in Europe. The percentile composition, the so-called fingerprint, showed significant differences between the southern part and the northern part for both FRs and PFASs, but also great similarities between some of the rivers with the highest measured PFASs concentrations. The highest loads of both FRs and PFASs were detected in Delångersån, which is one of the smaller rivers screened and likely to be affected by a nearby industrial point source. The European environmental quality standard of 0.65 ng L-1 of perfluorooctane sulfonic acid (PFOS) was exceeded in 12 of all 44 sampled rivers.

Tidigare studier har visat på höga halter av per- och polyfluorerade alkylsubstanser (PFAS) ilakvatten från avfallsanläggningar. Avfallsanläggningar i Sverige har idag inga krav på attrena bort PFAS från lakvatten, och anläggningarna har generellt inte ett reningssystem som äranpassat för att rena den typen av ämnen. EU stramar hela tiden åt kraven kring utsläpp ochanvändning av PFAS och det kan därför vara bra för en avfallsanläggning att ha översikt påhur mycket PFAS det släpps ut från deponi- och avfallsverksamheten och vilka eventuellaåtgärder som skulle kunna vidtas för detta problem. I denna uppsats används analysresultat av22 PFAS ämnen från nio provtagningspunkter på Gärstad avfallsanläggning, för attundersöka avfallsanläggningens utsläpp av PFAS. Resultaten för studien visar att deuppmätta värdena för summa PFAS 22 för provpunkterna ligger mellan 410 ng/l – 58 000ng/l. PFAS ämnen med kortare kedja (4 – 8 kol) har uppmätts i högre halter än de med längrekedja (9 – 13 kol). Resultaten visade även högre halter av perfluorerade karboxylater (PFCA)än perfluorerade sulfonsyror (PFSA). / Previous studies have shown high levels of per- and polyfluorinated alkyl substances (PFAS)in leachate from waste facilities. Waste facilities in Sweden currently have no requirements topurify PFAS from leachate, and the facilities generally do not have a treatment system that isadapted to purify this type of substances. The EU is constantly tightening the requirementsregarding the release and use of PFAS, and it can therefore be good for a waste facility tokeep track of how much PFAS is released from landfill and waste operations and whatpossible measurements could be taken for this problem. In this essay, analysis results of 22PFAS substances from nine sampling points at Gärstad waste facility have been used, toinvestigate the waste facility's discharge of PFAS. The results of studies show that themeasured values for total PFAS 22 at the sampling spots are between 410 ng/l - 58,000 ng/l.PFAS substances with a shorter chain (4 – 8 carbons) have been measured at higherconcentrations than those with a longer chain (9 – 13 carbons). The results also showedhigher levels of perfluorinated carboxylic acids (PFCAs) than perfluorinated sulfonic acids(PFSAs).

This thesis focuses on the state-of-the-art spectroscopic approaches in studying polymer electrolytes for proton exchange membrane fuel cells. With the aim to optimize architectural and chemical design of hydrogen fuel cells, a variety of perfluorosulfonic acid (PFSA) membranes were explored to establish characteristics that ultimately improve PFSA electrolyte performance. The results of the detailed spectroscopic analyses helped to unveil a structure performance relationship. Solid-state nuclear magnetic resonance (ssNMR) spectroscopy was used to distinguish F and C environments, while scanning transmission X-ray microscopy coupled with X-ray absorption spectroscopy provided complementary chemical structural information with direct access to S and O environments. The combination of these two techniques provided advantages in identifying subtle chemical alterations in PFSAs. Furthermore, a novel ssNMR technique was developed with the purpose of probing local dynamics from the polymer perspective. This ¬¬19F dipolar recoupling ssNMR approach was validated and applied to PFSA membranes by monitoring the normalized double quantum build-up curves as a function of relative humidity (%RH) and temperature, and the polymer side chain showed higher local motion as response to temperature and %RH elevation compared to the backbone. The effective dipolar coupling constant was extracted to represent local dynamics and compared amongst tested PFSAs. A standardized metric, the dynamic order parameter, was also introduced and applied to the materials to quantitatively compare them within the same class. This new method provided an alternative way to extract site-specific local dynamics profile for materials with multiple resonances. Additionally, the combination of in situ fuel cell performance evaluation and ex situ ssNMR characterization created a connection between fundamental chemistry and bulk electrochemical measurements. As the first study to correlate these physicochemical properties to material performances, this work parameterized the structural impact at a molecular level and provided insight into improving polymer electrolyte materials. / Thesis / Doctor of Philosophy (PhD) / Proton exchange membrane fuel cells, which help to reduce the reliance on fossil fuels by locally producing only water and heat, have received a significant amount of research attention as an alternative power generator for vehicular and stand-alone energy applications. Perfluorosulfonic acid (PFSA) membranes, the most common commercial polymer electrolyte materials, have been investigated using modern analytical spectroscopies. Solid-state nuclear magnetic resonance (ssNMR) spectroscopy and synchrotron-based scanning transmission X-ray microscopy were used in elucidating material compositions with complementary information. Moreover, an advanced ssNMR method was developed and applied to a variety of PFSAs. Polymer backbones and side chains were separated spectroscopically, and were distinguished based on different local dynamics profiles extracted from the ssNMR experiments. Additionally, bulk material performance evaluations from electrochemical analyses were correlated to PFSA side chain local dynamics profiles. The integrated spectroscopic study illustrated in this thesis provided insight into understanding the structure-performance relationship of PFSA electrolytes.

The focus of this dissertation was to investigate the influence of sidechain structure and sidechain content on the morphology and physical properties of perfluorosulfonic acid ionomer (PFSA) membranes. One of the primary objectives was to characterize the thermomechanical relaxations for short sidechain PFSAs developed by 3M and Solvay, as well as a new multi-acid sidechain perfluoroimide acid ionomer (PFIA) from 3M. Partial neutralization experiments played a key role in systematically manipulating the strength of the electrostatic interactions between proton exchange groups on each sidechain, leading to the elucidation of the molecular-level motions associated with multiple thermal relaxations observed by dynamic mechanical analysis (DMA). Particularly, 3M PFSA and Solvay Aquivion lack an observable β-relaxation in the sulfonic acid-form that is observed in the long sidechain PFSA, Nafion. By varying the strength of the physically-crosslinked network through exchanging the proton on the sulfonic acid groups for large counterions, we were able to conclude that the shorter sidechain length and increase in ion content in the 3M PFSA and Solvay Aquivion serves to restrict the mobility of the polymer backbone such that the onset of segmental motions of the main chains is not observed at temperatures below the α-relaxation temperature, where destabilization of the physically crosslinked network occurs. As a complementary technique to DMA for probing the relaxations in PFSAs, we introduced a new pretreatment method for differential scanning calorimetry (DSC) measurements that uncover a thermal transition in H+-form 3M PFSA, Aquivion, and Nafion membranes. This thermal transition was determined to be of the same molecular origin as the dynamic mechanical α-relaxation temperature in H+-form PFSAs, and the β-relaxation temperature in tetrabutylammonium (TBA+)-form PFSAs. The thermomechanical relaxations in multi-acid sidechain 3M PFIA were also investigated. Interestingly, the additional acidic site on PFIA led to unexpected differences in thermal and mechanical properties, including the appearance of a distinct glass transition temperature otherwise not seen in PFSA ionomers. We utilized small-angle X-ray scattering (SAXS) studies to probe the differences in aggregate structure between the PFIA and PFSA membranes in order to uncover the morphological origin of the anomalous thermomechanical behavior in PFIA membranes. Larger aggregate structures for PFIA, compared to PFSA, incorporate intervening fluorocarbon chains within the aggregate, resulting in increased spacing between ions that reduce the collective electrostatic interactions between ions such that the onset of chain mobility occurs at lower temperatures than the α-relaxation for PFSA. The SAXS profiles of PFSAs showed two scattering features resulting from scattering between crystalline domains and ionic domains distributed throughout the polymer matrix. In order to fit the "ionomer peak" to models used for the PFIA and PFSA aggregate structure determination, we presented a method of varying the electron density of the ionic domains by using different alkali metal counterions as a tool to make the intercrystalline feature indistinguishable. This allows for isolation of the ionomer peak for better fits to scattering models without any interference from the intercrystalline peak. Lastly, an investigation of annealing PFSAs of different sidechain structures in the tetramethylammonium (TMA+) counterion form above their α-relaxation showed a profound crystalline-like ordering of the TMA+ counterions within the ionic domains. This ordering is maintained after reacidification and leads to improved proton conductivity, which indicates that this method can be used as a simple processing method for obtaining improved morphologies in proton exchange membranes for fuel cell applications. / Doctor of Philosophy / Hydrogen fuel cells offer an environmentally friendly, high efficiency method for powering vehicles, buildings, and portable electronic devices. At the center of a hydrogen fuel cell is a polymer membrane that contains ionic functionalities, which conduct hydrogen ions (protons) from the anode to the cathode while preventing conduction of electrons. The electrons travel through an external circuit to produce electricity, while the protons travel through the polymer membrane and meet with oxygen on the other side to produce water, the only byproduct of a hydrogen fuel cell. The efficiency of this process relies on the ability of the polymer membrane to conduct protons, and the lifetime of a fuel cell depends on the mechanical stability of this membrane. Perfluorosulfonic acid ionomers are good candidates for use as polymer membranes in hydrogen fuel cells due to their Teflon backbone that provides mechanical stability and their sulfonic acid functionalities that form channels for proton conduction. In this work, we probe the structure-property relationships of different perfluorosulfonic acid ionomers for use as fuel cell membranes. We focus on thermal analysis techniques to develop a fundamental understanding of the effect of chemical structure and sulfonic acid content on the temperature-induced mobility of the polymer chains in these ionomers. This mobility at elevated temperatures can be utilized to rearrange the morphological structure of perfluorosulfonic acid ionomer membranes in order to enhance proton conductivity and mechanical integrity.

Ce travail de thèse a pour but de suivre le comportement du liant ionomère après vieillissement en condition réelle d'utilisation de la pile. Dans un premier temps, diverses techniques de caractérisation en phase solide ont été utilisées afin d'étudier le ionomère présent dans les électrodes. La majeure partie de ces techniques se sont avérées insatisfaisantes pour le suivi du vieillissement du ionomère. Seule l'analyse par diffraction rayon X (DRX) a mis en avant un changement d'organisation structurale du ionomère dans les électrodes. Par la suite, nous avons choisi de caractériser le ionomère en solution après extraction par l'eau. Préalablement, un protocole de quantification en 2 à 3 étapes, dans lequel intervient une quantification via le rapport signal-sur-bruit (S/N), a été mis en place afin de quantifier le Nafion® et autres petites molécules fluorés. L'extraction Soxhlet a ensuite été réalisée sur les électrodes permettant de révéler la présence d'un produit de dégradation hydrosoluble après fonctionnement en pile, à la fois en cathode et en anode. Enfin, la macération des électrodes dans le diméthylacétamide (DMAc) a permis d'extraire le polymère Nafion® ainsi que deux acides : l'acide trifluoroacétique (TFA) et l'acide triflique (TFI). En conclusion, la corrélation de l'ensemble des observations nous a permis de proposer un mécanisme de dégradation du liant ionomère présent dans les électrodes. / The purpose of this study was to follow the behavior of ionomer binder after fuel cell operation. First, a series of techniques were used to investigate to characterize ionomer in electrode at solid state. Most of them were inefficient to study ionomer degradation. Only X-Ray Diffraction (XRD) pointed out a structural change of the binder in electrodes. Second, it has been decided to characterize ionomer in liquid state after water extraction. But first of all, a quantitative 19F NMR protocol composed of two to three steps, with a first step using a quantification through signal-to-noise ratio (S/N), was establish in order to quantify Nafion® and degradation products. Soxhlet extraction performed on electrodes allowed to detect a degradation product water-soluble. Finally, extraction with organic solvent (Dimethylacetamide) allowed to extract Nafion® and two acid: trifluoroacetic acid (TFA) and triflic acid (TFI) from electrodes. In conclusion, correlation between observation and literature allowed us to propose a degradation mechanism of ionomer in electrodes.

La production de membranes échangeuses de protons (PEM) robustes et présentant une conductivité élevée est essentielle pour le développement à grande échelle de dispositifs de stockage et de conversion de l’énergie tels que les piles à combustible (PEMFC) et les électrolyseurs (PEMWE). Ces travaux de thèse portent sur la préparation et la caractérisation de membranes composites préparées à partir d’acide perfluorosulfonique, à chaine latérale courte (SSC-PFSA), de type Aquivion®, et de fibres de polymères obtenues par filage électrostatique. Cette dernière technique permet de préparer des matériaux fibreux à porosité élevée, caractérisés par la présence de fibres de diamètres sub-micrométriques, et pouvant être utilisés comme renfort mécanique des membranes ionomères. Le polysulfone a été retenu comme constituant des fibres étant donné ses stabilités mécanique et chimique élevées d’une part et pour la possibilité de modifier ses propriétés physico-chimiques par fonctionnalisation, d’autre part. Ces membranes comportant une distribution homogène des nanofibres dans toute leur épaisseur ont été préparées à partir d’un procédé d’imprégnation Des membranes renforcées, Aquivion®-PSU, basées sur un PFSA dont le poids équivalent (EW) varie entre 700 et 870 g.mol-1 et dont la concentration massique de fibres varie entre 5 et 18 %, ont été préparées. Les membranes renforcées sont caractérisées par des faibles gonflements volumique et surfacique et par une rigidité plus élevée en comparaison des membranes non renforcées de même EW. La perméabilité a l’hydrogène a engluement été réduite. Les améliorations en terme de propriétés mécaniques et dimensionnelles n’ont pas amené à une diminution significatif de la conductivité protonique, qui été maintenue aux mêmes valeurs des membranes non renforcée. Les assemblage membrane-électrode (AME) préparés à partir de ces membranes composites ont montré des caractéristiques i/V intéressantes et prometteuses (1.76 V à 2 A/cm²).Des Polysulfones fonctionnalisés avec le 1,2,3 triazole portant des groupements alkyle ou aryle ont été préparés par une voie de synthèse rapide et a haute rendement assistée par micro-ondes. Les nanofibres electrofilées de PSU fonctionnalisé avec le 4-ethyl-1,2,3-triazole (PSUT), avec un degré de fonctionnalisation en espèce triazole de 0.3 et 0.9 par unité répétitive de PSUT ont été intégrées à une matrice Aquivion®. L’objectif de ces travaux est d’améliorer la stabilité mécanique des membranes composites à partir des interactions acido-basiques PFSA-PSUT (réticulation ionique). Les membranes Aquivion®-PSUT sont caractérisées par une rigidité, une dureté et une ductilité plus élevées en comparaison des membranes Aquivion® renforcées par les fibres de PSU non fonctionnalisées. Une diminution du gonflement volumique et surfacique a également été observée sans perte de la conductivité jusqu’à une concentration massique de fibres de 12 %. Les AME préparés à partir de membranes renforcées Aquivion®-PSUT (12%) sont caractérisés par les mêmes propriétés courant/tension, en monocellule de pile à combustible fonctionnant à 80 °C et 100 % d’humidité relative, que ceux préparés à partir d’Aquivion®. / The preparation of highly proton conducting and durable proton exchange membranes (PEM) for low temperature fuel cells (PEMFC) and electrolysers (PEMWE) is crucial for the large scale application of these energy conversion/storage devices. This PhD thesis focuses on the preparation and characterisation of composite membranes based on highly conducting Aquivion® short side chain perfluorosulfonic acid (PFSA) and polymer fibres obtained by electrospinning. This technique allows the preparation of highly porous mats of fibres with sub-micrometric diameters that can act as an efficient mechanical reinforcement for ionomer membranes. The chosen polymer is the mechanically robust and chemically stable polysulfone (PSU), which can also been functionalised to modify its physico-chemical properties. Reinforced PEM with fibres homogeneously dispersed through the entire membrane cross-section have been realised by a fast and efficient impregnation process.Aquivion®-PSU reinforced membranes based on PFSA with equivalent weight (EW) ranging from 700 to 870 g mol-1 and fibre loading ranging from 5 to 18 wt% have been prepared. They showed reduced volume and area swelling and higher stiffness with respect to non-reinforced membranes with the same EW. The hydrogen crossover was also reduced. The improvement in mechanical and dimensional properties was not detrimental for the in-plane proton conductivity that was kept at the same value of non-reinforced membranes. Membrane-electrode assemblies (MEA) based on these composite PEM show promising i/V characteristics in PEMWE (1.76 V at 2 A cm-2).Polysulfones functionalised with 1,2,3-triazole bearing alkyl and aryl ring substituents have been synthesized by a fast and high-yield chemical route involving the azide-alkyne cycloaddition reaction assisted by microwaves as last step. Electrospun nanofibers of polysulfone functionalised with 4-epthyl-1,2,3-triazole (PSUT) with a degree of functionalisation of 0.3 and 0.9 triazole moiety per PSUT repeat unit have been embedded into the Aquivion® matrix. The aim of this study was to further improve the mechanical properties of the membrane by PFSA-PSUT acid-base interactions (ionic crosslinking). Aquivion®-PSUT membranes showed enhanced mechanical stiffness, toughness and ductility with respect to Aquivion® membranes reinforced with the non-functionalised polymer with the same EW and fibre loading. Reduced volume and area swelling have also been observed with no drop of proton conductivity until a fibre loading of (12 wt%). MEA based on Aquivion®-PSUT reinforced membrane with 12 wt% fibre loading showed identical fuel cell polarisation curve with respect to a MEA based on Aquivion® at 80 °C and 100 % of relative humidity (RH).

Climate change has propelled the development of alternative power sources that minimize the emission of greenhouse effect gases. Widespread commercialization of polymer electrolyte membrane fuel cell (PEM-FC) technology for transportation and stationary applications requires cost-competitiveness with improved durability and performance. Advantages compared to battery electric vehicles include fast refueling and long distance range. One way to improve performance and minimize costs of PEM-FC involves the optimization of the nanostructure of the catalyst layer. The rate limiting oxygen reduction reaction occurs at a triple-phase interface in the cathode catalyst layer (CL) between the proton conductor perfluorosulfonic acid, PFSA, the Pt catalyst particles decorating the electron conductor carbon support and gaseous O2 available through the porous framework of the carbon support. Visualization and quantitation of the distribution of components in the CL requires microscopy techniques. Electron and X-ray microscopy have been used to characterize the distribution of the PFSA relative to the carbon support and porosity in CLs. Understanding and limiting the analytical impact of radiation damage, which occurs due to the ionizing nature of electrons and X-rays, is needed to improve quantitation, particularly of PFSA. This thesis developed scanning transmission X-ray microscopy (STXM) methods for quantitation of damage due to electron and soft X-ray irradiation in PFSA materials. Chemical damage to PFSA when irradiated by photons and electrons is dominated by fluorine loss and CF2-CF2 amorphization. The quantitative results are used to set maximum dose limits to help optimize characterization and quantitation of PFSA in fuel cell cathode catalyst layers using: analytical electron microscopy, X-ray microscopy, spectromicroscopy, spectrotomography, spectroptychography and spectro-ptycho-tomography. / Thesis / Doctor of Philosophy (PhD) / Polymer electrolyte membrane fuel cells are an alternative, environmentally friendly power source for transportation and stationary applications. Major challenges for mass production include cost competitiveness, improved durability and performance. A key component to enhance the performance and lower costs involves understanding and improving the spatial distribution of the perfluorosulfonic acid (PFSA) polymer in the catalyst layer. The ionizing nature of electrons and X-rays used in microscopy characterization tools challenges PFSA characterization since this material is radiation sensitive. This thesis developed measurement protocols and methods for quantitative studies of radiation damage to PFSA and other polymers using scanning transmission X-ray microscopy. The chemical changes to PFSA films irradiated with photons, electrons and ultraviolet (UV) photons were studied. The quantitative results identify limits to analytical electron and soft X-ray microscopy characterization of PFSA. The results are used to optimize methods for soft X-ray microscopy characterization of PFSA in fuel cell applications.